Dons still have a sell-on clause with Spurs for Dele
The 24-year-old left Stadium MK in January 2015 when he was 19, but returned to the club on loan to help Dons secure promotion to the Championship.
Dons' had several clauses in the deal with Spurs, including a sell-on clause which would see Dons given another payment should he leave the club.
It had been rumoured though that the clause had been bought out by Spurs, but in explaining why Rhys Healey's transfer to Toulouse was undisclosed, Mr Cullen explained why he also cannot reveal the details of the sell-on Dons have for Dele.
"I'm often asked about the sell-on on Dele Alli if he were to leave Spurs," he said. "I cannot tell you because if I did, that sell-on could be compromised so it has to remain confidential."